Commissioning of Upgrades to T6 to Study Giant Planet Entry

Commissioning of Upgrades to T6 to Study Giant Planet Entry

The Ice Giants, Uranus and Neptune, represent a largely unexplored, interstitial class of planetary objects that fit between the Gas Giants and the smaller terrestrial worlds, such as Earth, in terms of both size and elemental composition and are a missing link in our understanding of extrasolar planetary evolution. The scientific potential of a mission to the Ice Giants is well recognised and has been identified by NASA and ESA as a high priority on several occasions, most recently in the 2023 - 2032 Decadal Survey. The payload capacity of such a spacecraft is limited by the heat shield thickness, which must be sized conservatively
due to a lack of reliable data for convective and radiative heat flux along the proposed entry trajectories. Major upgrades to the Oxford T6 Stalker Tunnel have been commissioned that allow study of Giant Planet entry trajectories including a flammable gas handling system, a
Mach 10 expansion nozzle, and a steel shock tube with optical access. Initial testing has been completed in shock tube and expansion tunnel modes with peak shock speeds of 18.9 km/s
achieved with many options available to further increase performance. Convective heat flux and surface pressure were measured at several locations on a 45 °sphere cone model in expansion tunnel mode. Measurements of the radiating shock layer were made in shock tube mode to assess the effect of CH4 concentration. The magnitude of spectral radiance is strongly affected by the concentration of CH4 in the test gas. Spectral fitting with the NEQAIR program shows
that radiation in the 410 - 560 nm range is dominated by C2 and CH and has allowed the spatial evolution of mode temperatures and species concentrations to be extracted. This work establishes the first high enthalpy Giant Planet entry test bed in Europe.

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